With the basic spin there is always one foot on the floor. It is used to transition from one position on the pole or from facing one direction to facing another direction. There are many add-ons to the basic spin, one of them I show you in this video, the back hook spin. This can be used to get to the floor for some floor work or you can land on your feet to continue pole work.
Note: this spin can also be paired with the pirouette, a spin I taught in early May.